In the prior art there are many types of printers that are used with data processing equipment. Examples of such prior art printers are impact printers which include daisy wheel and dot matrix printers, and laser printers which use a copier process coupled with a laser that writes the material to be printed to an image drum within the printer. There are also many other types of prior art printers. Such prior art printers usually utilize sheet paper.
Paper handling mechanisms for high-speed sheet paper printers are typically very complex and very expensive. To reduce the complexity and cost some high-speed prior art printers utilize a roll of paper that passes through the printer mechanisms as one continuous web and, after printing is accomplished, the paper is cut into sheets and is output either directly from the printer or is output via prior art collator mechanisms. There have been problems with these prior art roll paper printers in that the tension on the paper web is varied throughout the printer mechanisms caused by the mechanisms starting and stopping, and by different pressures being applied to the paper by drive rollers. The result has been variable elongation of the paper web. The result of variable elongation of the paper web with two sided printing being performed is a misregistration of the print on both sides of the paper. In addition, the paper cutting mechanism found in such printers has not been able to be operated properly to cut the paper into sheets. That is, printing on each sheet after cutting the web is not vertically positioned properly. The printing is near the top of a sheet, near the bottom of a sheet, and sometimes properly positioned vertically in the middle of a sheet. These problems have all contributed to preventing roll paper printers from becoming popular.
Accordingly, there is a need in the art for a roll paper printer that can regulate the tension on the paper web and keep it uniform as it passes through the mechanisms in the printer. This greatly reduces the prior art problems enumerated above.